Walnuts 'lower breast cancer risk'

A new study has found that eating walnuts may help to reduce the risk of developing breast cancer.

Omega-3 fatty acids, antioxidants and phytosterols are all thought to play a part in reducing the risk of the disease.

Researchers led by Elaine Hardman of the Marshall University School of Medicine found that mice fed the human equivalent of two ounces (56.7g) of walnuts per day developed fewer and smaller tumours than a control group.

The findings, recently presented to the American Association for Cancer Research annual meeting, also showed that mice fed on walnuts who did develop tumours, did so more slowly, and produced smaller tumours.

Hardman said the results showed that walnuts could contribute to a healthy diet that could help to reduce breast cancer in humans.

Some research has suggested that walnuts can reverse some of the damage done by fatty food to the arteries, if eaten at the end of a meal.

Omega-3 fatty acids were shown in chemical analysis to have played a role in protection against cancer, although other ingredients also appeared to be active.

Nutrition experts said they had tended to focus on the evidence that nuts could reduce the risk of heart disease, rather than their potential for acting against cancer.

British Nutrition Foundation scientist Anna Denny said that while nuts are high in fat and therefore calories, the fatty acids in nuts were predominantly 'good' unsaturated fatty acids.

She said other components of nuts might contribute to a reduction in heart disease and cancer risk, including fibre and 'bioactive' compounds like phytosterols and flavonoids.

But she said more research was needed before the specific health benefits of nuts could be attributed to bioactive compounds, because of the complexity of the mixture of compounds in nuts.

Cancer Research spokeswoman Josephine Querido, of the charity Cancer Research UK said there was still not enough evidence to show that eating walnuts could prevent breast cancer in humans.

However, she said that a healthy balanced diet with plenty of fruit and vegetables played an important part in reducing cancer risk generally.

She said the strongest risk factor in breast cancer was still age, with 80% of tumours found in women of 50 and over, and emphasised the importance of attending screening programmes for women over that age.

She said keeping a healthy body weight, limiting alcohol intake and taking regular exercise could also help reduce the risk of breast cancer.

Walnuts have been shown to contain an amino acid called arginine, used by the body to produce nitric oxide.

Previous studies have also found antioxidants and a plant-based omega-3 fatty acid known as alpha-linolenic acid, or ALA, both of which have been linked to health benefits.